Deep Venous Thrombosis and Pulmonary Embolism

Deep vein thrombosis (DVT) and acute pulmonary embolism (PE)—commonly described together as one clinical entity, venous thromboembolism (VTE)—confront the clinician with diagnostic and therapeutic challenges. This issue of Seminars in Respiratory and Critical Care Medicine contains a series of excellent overviews on VTE, written by an international group of European experts, and includes discussions on epidemiology, diagnosis, triaging, prevention, and treatment of this often occurring and potentially fatal disease.

Baglin from Cambridge, United Kingdom, provides us with an excellent update on the inherited and acquired risk factors for venous thromboembolism. The development of symptomatic venous thrombosis is highly dependent on gene–environment interaction. Although testing for heritable thrombophilia aids in explaining the etiology of VTE—and may be relevant to patients' knowledge of their disease—the results of this testing rarely influence duration of anticoagulation. The optimal diagnostic management of patients presenting with clinically suspected acute pulmonary embolism is discussed by Mos and colleagues from Leiden, The Netherlands. Clinical outcome studies have demonstrated that PE can be safely ruled out in up to 30% of patients, who have an unlikely clinical probability by clinical decision rule in combination with a normal D-dimer test result. Multidetector computed tomographic pulmonary angiography (CTPA) is the imaging test of choice because of its high sensitivity and specificity. Special paragraphs are devoted to patients presenting with recurrent symptoms, and the diagnostic management of suspected PE in elderly patients, pregnant patients, and patients with malignancy.

Compression ultrasonography (CUS) is the method of choice in the diagnostic management of clinically suspected DVT. It is highly accurate for proximal DVT but lacks sensitivity and specificity for distal DVT. There are several ways to overcome this limitation as described in a thoughtful review by Guanella and Righini from Geneva, Switzerland. They discuss the advantages and disadvantages of serial limited CUS and single complete CUS, which are both reliable diagnostic options for the management of patients with suspected DVT.

Tan and colleagues discuss the clinical dilemma of accurately diagnosing recurrent VTE. Neither clinical decision rules nor D-dimer tests have been fully validated for patients presenting with a recurrent VTE event, and persistent residual abnormalities after the first or previous event often render imaging interpretation difficult. It is suggested to perform standardized baseline examination after anticoagulation cessation for either DVT or PE.

Triaging of patients with acute PE according to the most recent European guidelines provides the best treatment for the different categories of patients. Sanchez and colleagues from Paris, France, give us a timely overview of different categories of patients, ranging from high-risk patients presenting with shock or signs of hypoperfusion, to normotensive patients, who have right ventricular dysfunction and are at intermediate risk of severe complications, and finally patients with normotensive PE without right ventricular constraint who have a low risk of death and complication. Several risk scores combining different risk factors are also discussed.

Although pharmacological prophylaxis reduces the risk of PE by 75% in general surgical patients and by 57% in medical patients and its use in patients at moderate to high risk for VTE is strongly recommended by international guidelines, several studies have shown that nearly half of the patients undergoing major surgery or hospitalized for medical illnesses do not receive appropriate antithrombotic prophylaxis. Bozzato and colleagues from Varese, Italy, discuss different strategies to reduce this discrepancy.

According to international guidelines, including those of the American College of Chest Physicians (ACCP), interventional approaches for acute treatment of VTE such as catheter-guided thrombolysis, thrombosuction, and vena cava filter placement should be used only in selected populations. In an extensive review Imberti and colleagues from Piacenza, Italy, summarize the literature on these interventional approaches in VTE treatment and review the appropriate indications for their use in daily clinical practice.

Standard anticoagulation therapy for acute VTE consists of a course of low molecular weight heparin or fondaparinux followed by vitamin K antagonists for a period of at least 3 months. Eichinger and Kyrle from Vienna, Austria, discuss the indications for a prolonged course of vitamin K antagonists as well as specific tools, including coagulation markers and clinical decision models, which combine clinical features and laboratory markers to guide the duration of anticoagulation.

Recent extensive clinical research has focused on the development of new anticoagulant drugs that could be administered orally at a fixed dose, with fewer food and drug interactions and no need for monitoring or dose adjustment. In clinical trials these new oral compounds were demonstrated to be noninferior to conventional treatment in patients with acute VTE. Le Gal and Mottier from Brest, France, discuss several remaining issues, such as the lack of a specific antidote and monitoring laboratory tests. The potential role of these new drugs, including facilitating outpatient management of VTE and improving the risk–benefit balance of prolonged anticoagulation, are also discussed.

Chronic thromboembolic pulmonary hypertension (CTEPH) is a rare but very relevant complication after episodes of acute PE. Klok and colleagues from Leiden, The Netherlands, provide us with an in-depth review containing a concept of the underlying pathophysiological mechanism, up-to-date diagnostic management, and treatment of this devastating disease entity.

Venous thrombosis and arterial thrombosis have traditionally been considered as separate diseases. Prandoni and colleagues from Padua, Italy, provide evidence for a link between venous and arterial thrombosis. Several risk factors are shared, there are conditions accounting for both entities, and several studies have shown that patients with idiopathic VTE are at increased risk of arterial thrombotic complications compared with patients without VTE. A common biological pathway stimulating coagulation and inflammation for both diseases is hypothesized.

Overall, this issue is enhanced by the highly readable efforts of this group of outstanding experts. We owe many thanks to the authors for their excellent contributions.

We hope the offerings herein will provide the readership with useful information and will stimulate new thoughts for improvement of patient care and research in this dynamic field.